Semiconductor device

Abstract

A semiconductor device includes a barrier layer having a nitrogen polarity on an upper surface, a channel layer on the barrier layer, the channel layer having a nitrogen polarity on an upper surface, a first cap layer on the channel layer, the first cap layer having a nitrogen polarity on an upper surface, and a dielectric film in contact with the upper surface of the first cap layer. The first cap layer is an aluminum nitride layer.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a barrier layer having a nitrogen polarity on an upper surface;   a channel layer on the barrier layer, the channel layer having a nitrogen polarity on an upper surface;   a first cap layer on the channel layer, the first cap layer having a nitrogen polarity on an upper surface; and   a dielectric film in contact with the upper surface of the first cap layer,   wherein the first cap layer is an aluminum nitride layer.   
     
     
         2 . A semiconductor device, comprising:
 a barrier layer having a nitrogen polarity on an upper surface;   a channel layer on the barrier layer, the channel layer having a nitrogen polarity on an upper surface;   a first cap layer on the channel layer, the first cap layer having a nitrogen polarity on an upper surface; and   a dielectric film in contact with the upper surface of the first cap layer,   wherein a proportion of aluminum in Group III elements is 52% or more in the upper surface of the first cap layer.   
     
     
         3 . The semiconductor device according to  claim 1 ,
 wherein a thickness of the first cap layer is 0.2 nm or greater and less than 2.0 nm.   
     
     
         4 . The semiconductor device according to  claim 1 , further comprising:
 a second cap layer between the channel layer and the first cap layer, the second cap layer having a nitrogen polarity on an upper surface,   wherein a proportion of aluminum in Group III elements in the second cap layer is lower than a proportion of aluminum in the Group III elements in the first cap layer.   
     
     
         5 . The semiconductor device according to  claim 1 , further comprising:
 a gate electrode on the dielectric film.   
     
     
         6 . The semiconductor device according to  claim 2 ,
 wherein a thickness of the first cap layer is 0.2 nm or greater and less than 2.0 nm.   
     
     
         7 . The semiconductor device according to  claim 2 , further comprising:
 a second cap layer between the channel layer and the first cap layer, the second cap layer having a nitrogen polarity on an upper surface,   wherein a proportion of aluminum in Group III elements in the second cap layer is lower than a proportion of aluminum in the Group III elements in the first cap layer.   
     
     
         8 . The semiconductor device according to  claim 2 , further comprising:
 a gate electrode on the dielectric film.